Stent Graft Fenestration

ABSTRACT

A method for creating a channel through a foreign material located in a body of a patient, the foreign material defining a material first surface and a substantially opposed material second surface, the channel extending through the foreign material between the material first and second surfaces, the method using an apparatus including an electrode, the method comprising: positioning the electrode substantially adjacent to the material first surface; energizing the electrode with a radiofrequency current; and using the electrode energized with the radiofrequency current to deliver energy into the foreign material to create the channel, wherein the foreign material is included in a stent graft.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/905,448, filed on Oct. 1, 2007, which claims the benefit ofU.S. provisional patent application Ser. No. 60/827,466 filed on 29^(th)Sep. 2006. This application further claims the benefit of U.S.provisional application No. 61/448,578, filed on Mar. 2^(nd), 2011. Allof these US patent applications and provisional patent applications arehereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates generally to methods and devices usable todeliver energy within the body of a patient. More specifically, thepresent invention is concerned with a method for creating a channelthrough a stent graft.

BACKGROUND OF THE INVENTION

There are many situations in which it would be desirable to create achannel through a stent graft located in a body of a patient. Forexample, the following two papers give examples of such procedures:McWilliams et al., “In Situ Stent-Graft Fenestration to Preserve theLeft Subclavian Artery” Journal of Endovascular Therapy Vol. 11, No. 2,pp. 170-174; and McWilliams et al. “Retrograde Fenestration ofEndoluminal Grafts From Target Vessels: Feasibility, Technique, andPotential Usage.” Journal of Endovascular Therapy: Vol. 10, No. 5, pp.946-952, the contents of which are incorporated herein by reference intheir entirety.

In some cases, a graft composed of foreign material including asubstantially tubular supporting structure, for example a stent, needsto be positioned within a vessel of the body of the patient. However,because of the configuration of the vessel, side branches extending fromthe vessel may be obstructed by the graft. Restoration of flow throughthese side branches is relatively difficult to perform with apercutaneous needle because of the relatively large forces required.Also, the relatively large forces exerted onto the needle create a riskthat the needle will pass through the foreign material suddenly anddamage adjacent tissues.

Against this background, there exists a need in the industry to providea novel method for creating a channel through a stent graft.

SUMMARY OF THE INVENTION

In contrast to the commonly understood mechanisms of radiofrequencyperforation, it has been unexpectedly found that, as described furtherherein below, a radiofrequency-based apparatus is usable to createchannels through foreign materials which may be, for example,substantially synthetic materials.

A method for creating a channel through a foreign material located in abody of a patient, said foreign material defining a material firstsurface and a substantially opposed material second surface, saidchannel extending through said foreign material between said materialfirst and second surfaces, said method using an apparatus including anelectrode, said method comprising:

-   -   positioning said electrode substantially adjacent to said        material first surface;    -   energizing said electrode with a radiofrequency current; and    -   using said electrode energized with said radiofrequency current        to deliver energy into said foreign material to create said        channel;    -   wherein said foreign material is included in a stent graft.

Examples of such foreign materials include any cellular-based material(in addition to biological tissue), as well as any synthetic materialthat absorbs water or that will melt at the operating temperature of theelectrode. For example, and non-limitingly, the foreign material has amelting temperature of less than about 150 degrees Celsius. In oneparticular example the foreign material includes a synthetic material.In another example the foreign material includes a material selectedfrom the group consisting of polyethylene terephthalate (PET), cotton, apolyester material and fabrics thereof.

In some embodiments of the invention, positioning of said electrodesubstantially adjacent to said material first surface is performedbefore energizing said electrode,

In some embodiments, the method further comprises advancing saidelectrode into said foreign material towards said material secondsurface while delivering said energy into said foreign material.

Furthermore, in some embodiments the method further comprises:delivering said energy into said foreign material for a predeterminedduration; and stopping delivery of said energy into said foreignmaterial after said predetermined duration. In an example of this, thepredetermined duration is from about 0.1 second to about 5 seconds. In aspecific example of this, the predetermined duration is from about 1second to about 2 seconds.

Advantageously, the proposed method allows an intended user torelatively easily create the channel using an apparatus that has beenadvanced through a relatively tortuous path through the body of thepatient, as minimal force is required be exerted onto the material withthe distal end region of the apparatus in order to create the channel.

In some embodiments of the invention, the proposed method is performedusing a sequence of a relatively small number of relatively quick andergonomic steps using devices substantially similar to existingradiofrequency perforation apparatuses.

In addition, the proposed method is relatively safe for biologicaltissues adjacent to the foreign material, which minimizes risks ofinjuring these biological tissues and of creating potentiallylife-threatening situations.

In some embodiments, the foreign material is included in a septal patchextending across an aperture formed in the septum of the heart of apatient. In other embodiments, the foreign material is included in astent graft occluding the ostium of a blood vessel.

Furthermore, in some embodiments of the method of the present inventionsaid body of said patient includes a body vasculature having a firstvessel and a second vessel branching off of the first vessel, and saidforeign material is included in a stent graft located within said firstvessel and occluding an opening of said second vessel.

In an example of such embodiments, said first vessel comprises anabdominal aorta and said second vessel comprises a renal arterybranching from said abdominal aorta at a renal artery ostium, and saidstent graft occludes said renal artery ostium. The method furthercomprises: positioning said electrode substantially adjacent to saidmaterial first surface includes positioning said electrode substantiallyadjacent to said renal artery ostium outside of said abdominal aorta;and using said electrode energized with said radiofrequency current todeliver said energy into said foreign material to create said channelincludes delivering said energy into said stent graft.

In another example of such embodiments, said first vessel comprises anabdominal aorta and said second vessel comprises a renal arterybranching from said abdominal aorta at a renal artery ostium, and saidstent graft occludes said renal artery ostium. The method furthercomprises: positioning said electrode substantially adjacent to saidmaterial first surface includes positioning said electrode substantiallyadjacent to said renal artery ostium inside of said abdominal aorta; andusing said electrode energized with said radiofrequency current todeliver said energy into said foreign material to create said channelincludes delivering said energy into said stent graft.

In still another example of such embodiments, said first vesselcomprises a thoracic aorta and said second vessel comprises a leftsubclavian artery branching from said thoracic aorta at a leftsubclavian artery ostium, and said stent graft occludes said leftsubclavian artery ostium. The method further comprises: positioning saidelectrode substantially adjacent to said material first surface includespositioning said electrode substantially adjacent to said leftsubclavian artery ostium outside of said thoracic aorta; and using saidelectrode energized with said radiofrequency current to deliver saidenergy into said foreign material to create said channel includesdelivering said energy into said stent graft.

Furthermore, in another example of such embodiments, said first vesselcomprises a thoracic aorta and second vessel comprises a left subclavianartery branching from said thoracic aorta at a left subclavian arteryostium, and said stent graft occludes said left subclavian arteryostium. The method further comprises: positioning said electrodesubstantially adjacent to said material first surface includespositioning said electrode substantially adjacent to said leftsubclavian artery ostium inside of said thoracic aorta; and using saidelectrode energized with said radiofrequency current to deliver saidenergy into said foreign material to create said channel includesdelivering said energy into said stent graft.

In another embodiment, the method further comprises the steps of:monitoring a current output of said electrode; detecting one or moreover-currents if the current output exceeds a predetermined magnitudethreshold; determining an extent of the over-currents detected beforethe expiry of a predetermined time period; and controlling the deliveryof energy based on the extent of the over-currents detected.

Other objects, advantages and features of the present invention willbecome more apparent upon reading of the following non-restrictivedescription of preferred embodiments thereof, given by way of exampleonly with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings:

FIG. 1A, in a perspective view, illustrates an apparatus for creating achannel through a foreign material in accordance with an embodiment ofthe present invention;

FIG. 1B, in a front cross-sectional view taken along the line 1B-1B ofFIG. 1A, illustrates the apparatus of FIG. 1A;

FIG. 2, in a partial perspective view, illustrates a distal end regionof the apparatus of FIG. 1A;

FIG. 3A, in a partial perspective view, illustrates an embodiment of ahandle usable with the apparatus illustrated in FIGS. 1A to 2;

FIG. 3B, in a side cross-sectional view, illustrates the handle of FIG.3A;

FIGS. 3C and 3D, in perspective views, illustrate an embodiment of asecuring component usable with the handle shown in FIGS. 3A and 3B;

FIG. 4, in a flow chart, illustrates a method for creating a channel ina foreign material in accordance with an embodiment of the presentinvention;

FIGS. 5A and 5B, in schematic views, illustrate a method for creating achannel in a septal patch extending across an aperture formed in theheart of a patient in accordance with an embodiment of the presentinvention;

FIGS. 6A and 6B, in schematic views, illustrate a method for creating achannel in a stent graft extending across an ostium of a renal artery ofa patient in accordance with an embodiment of the present invention;

FIGS. 7A and 7B, in schematic views, illustrate a method for creating achannel in a stent graft extending across an ostium of a renal artery ofa patient in accordance with an alternative embodiment of the presentinvention;

FIGS. 8A and 8B, in schematic views illustrate a method for creating achannel in a stent graft extending across an ostium of a left SubclavianArtery (LSA) of a patient in accordance with an alternative embodimentof the present invention;

FIG. 8C is a right anterior oblique view illustrating a method forcreating a channel in a stent graft extending across an ostium of a leftSubclavian Artery (LSA) of a patient in accordance with an alternativeembodiment of the present invention;

FIG. 8D, in schematic view illustrates a method for creating a channelin a stent graft extending across an ostium of a left Subclavian Artery(LSA) of a patient in accordance with an alternative embodiment of thepresent invention;

FIGS. 9A and 9B, in schematic view illustrates a method for creating achannel in a stent graft extending across an ostium of a left SubclavianArtery (LSA) of a patient in accordance with an alternative embodimentof the present invention; and

FIG. 10 is a flow chart showing steps of a method in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION

Generally speaking, the proposed method is performed for creating achannel through a stent graft located in a body of a patient. The stentgraft may include foreign material defining a material first surface anda substantially opposed material second surface and the channel extendsthrough the foreign material between the material first and secondsurfaces. Typically, the method uses an apparatus including asubstantially elongated member defining a proximal end region and asubstantially longitudinally opposed distal end region, thesubstantially elongated member including an electrode located about thedistal end region.

The method includes positioning the electrode substantially adjacent tothe material first surface; energizing the electrode with aradiofrequency current; and using the electrode energized with theradiofrequency current to deliver energy into the foreign material tocreate the channel.

For example, the method is usable for restoring blood flow to a bloodvessel of a body of a human or animal, the blood vessel being occludedby a foreign material. In this case, the channel is created through theforeign material.

As a feature of the aforementioned aspects, in some embodiments of theinvention, the apparatus has a substantially atraumatic distal end, thusreducing the risk of unintentional perforation of a body vessel or othertissues. Also, the use of energy in creating the channel allows for thecreation of channels in foreign materials through which creation of suchchannels is difficult, if not impossible, to perform using mechanicalforce. In some embodiments, the method is performed using relativelysmall apparatuses, for example apparatuses having a relatively smalldiameter, which are therefore relatively easily introduced intorelatively small vessels.

With specific reference now to the drawings in detail, it is stressedthat the particulars shown are by way of example and for purposes ofillustrative discussion of embodiments of the present invention only,and that many alternative embodiments of the invention are within thescope of the appended claims.

For the purposes of this description, the term ‘proximal’ indicates nextto or nearer to the user, and the term ‘distal’ indicates further awayfrom the user, when the apparatus is in use.

Apparatus

Structure

As illustrated in FIG. 1, one embodiment of an apparatus 100 accordingto the present invention includes a substantially elongated member 102defining a distal end region 104 and a proximal end region 106. Thedistal end region 104 includes a distal tip 108 and an electrode 110located about the distal end region 104. The electrode 110 is usable asa radiofrequency energy delivery component. In the embodiment shown inFIG. 1, the apparatus 100 further comprises an actuator 112 fordirecting at least a portion of the distal end region 104 in a desireddirection.

The elongated member 102 may be electrically conductive and may beoperable to conduct electrical energy to the distal tip 108, and morespecifically to the electrode 110. In such embodiments, the elongatedmember 102 is also known as a core wire. In the illustrated embodiments,the elongated member 102 is at least partially covered with aninsulating material 114 for substantially preventing conduction ofelectrical energy to surrounding bodily tissue. In accordance with theseembodiments, the insulating material 114 may be made of any of a varietyof electrically insulating materials and may have any suitablethickness, provided that the elongated member 102 is at least partiallyelectrically insulated. In one particular embodiment, the insulatingmaterial 114 is at least about 0.1 mm thick. The elongated member 102may comprise a wire that is narrow enough to be navigated through ablood vessel. In some specific embodiments, the elongated member 102measures about 0.2 mm to about 1.0 mm in diameter.

In alternative embodiments, the insulating material 114 is discontinuousat one or more locations along the elongated member 102. For example, inone such embodiment, a number of discontinuities in the insulatingmaterial 114, along the length of the elongated member 102, create a‘banded’ appearance, wherein insulated regions are interleaved betweenelectrically exposed and conductive regions. In another embodiment, aregion of the insulating material 114 does not completely circumscribethe elongated member 102. For example, insulating material 114 maytraverse approximately 180 degrees of the circumference of the elongatedmember 102, leaving the remaining area electrically exposed. Any shapeor pattern of discontinuities may be present and the invention is notintended to be limited in this regard. Discontinuities in the insulatingmaterial 114 may affect the distribution of energy, for example currentdensity, around the elongated member 102 when the elongated member 102is used to deliver energy. Embodiments of the present inventioncomprising such discontinuities may be suitable for specificapplications, for example, when it is desirable to deliver energy alonga portion of the length of the elongated member 102 or to focus thedelivery of energy to a particular location or target site. In someembodiments, discontinuities in the insulating material 114 correspond,at least in part, to discontinuities in the structure of the elongatedmember 102. For example, in one specific embodiment, notches, describedin greater detail below, are present in the elongated member 102, thethickness of the insulating material 114 being reduced in the vicinityof the notches.

In some embodiments, at least a portion of the proximal end region 106of the elongated member 102 is electrically exposed, such that theelongated member 102 may be electrically coupled to an energy source,for example using an electrical connector.

In alternative embodiments, the elongated member 102 is made out of anelectrically insulating material. In such embodiments, the insulatingmaterial 114 is typically not required. For example, in someembodiments, the elongated member 102 is made out of nylon (e.g. Pebax),polyetheretherketone (PEEK), or polypropylene, and at least oneelectrode 110 is attached to the distal tip 108, the electrode 110 beingelectrically couplable to an energy source. In one particularembodiment, the electrode 110 is electrically coupled to the actuator112, which itself may be made of an electrically conductive material andwhich may be capable of being electrically coupled to an energy source.Alternatively, one or more electrodes 110 are attached to the elongatedmember 102, rather than to the actuator 112.

In some embodiments, at least a portion of the distal end region 104 isstructured to prevent unwanted damage to a body vasculature of a patientwhen the apparatus 100 is inserted therethrough. For example, as shownin FIG. 2, the distal tip 108 may have a substantially atraumatic shape,for example having a blunt or rounded edge, for preventing such damageas the apparatus 100 is maneuvered through the body vasculature. Inother embodiments, the distal tip 108 may be substantiallysemispherical, hemispherical, spherical or flattened, or may have anyother shape that is unlikely to damage tissues upon contact.Alternatively or in addition, in some embodiments, at least a portion ofthe distal end region 104 of the elongated member 102 has a reducedrigidity relatively to the proximal end region 106. The reduced rigiditymay serve to further decrease the ability of the elongated member 102 topuncture tissue, for example the tissue of a vessel wall, with theapplication of mechanical force. This reduced rigidity may be achievedby, for example, by the inclusion or substitution of a differentmaterial in the manufacture of the elongated member 102, by reducing theamount of material present in at least a portion of the distal endregion 104, or by reducing the diameter of the actuator 112. Materialmay be removed, for example, by using a latticework or otherdiscontinuous structural framework, or alternatively by thinning thewall of a portion of the elongated member 102.

In some embodiments, as seen in FIG. 1B, the elongated member 102defines a lumen 116, as will be described further herein below, and thewall thickness of the elongated member 102 tapers in the portion ofdistal end region 104 approaching the distal tip 108. For example, theelongated member 102 may taper from inside to outside, therebymaintaining a consistent outer diameter and having a changing innerdiameter. Alternatively, the elongated member 102 may taper from outsideto inside, thereby maintaining a consistent inner diameter and having achanging outer diameter, or from both the inside and the outside therebyhaving the outer diameter decrease and the inner diameter increase.

As has been mentioned above, the apparatus 100, as shown in theillustrated embodiments, includes an electrode 110 located about thedistal end region 104. The electrode 110 may be integral with one orboth of the elongated member 102 and the actuator 112 or may beotherwise attached to the distal tip 108. For example, the distal tip108 may be covered with an electrically conductive cap, the cap thusforming the electrode 110. In embodiments wherein the electrode 110 isnot integral with one or both of the elongated member 102 and actuator112, the electrode 110 may be otherwise electrically coupled to one orboth of the elongated member 102 and actuator 112 or to another wireoperable to electrically couple electrode 110 to an energy source. Forexample, in one embodiment, the electrode 110 is integral with theactuator 112 and may be associated with the distal tip 108 by beingpassed through the elongated member 102. Alternatively, when theapparatus 100 comprises a core wire, as described hereinabove, theelectrode 110 may be integral with the core wire.

The electrode 110 may be larger or smaller, or may have the samediameter, as the distal tip 108. In some embodiments, the electrode 110is sized to be operable to generate sufficient heat to create thechannel in the foreign material, when energy is supplied to theelectrode at a sufficient power level. In the context of the presentinvention, the term foreign material encompasses any material foreign tothe body being treated including synthetic materials. In one specificembodiment, the electrode may measure from about 0.40 mm to about 0.43mm in diameter and from about 1.2 mm to about 1.5 mm in length.

In the embodiment shown in FIG. 1B, as has been mentioned above, theelongated member 102 defines a lumen 116 extending at least partiallytherethrough. FIG. 1B shows one embodiment of a centrally locatedsubstantially circular lumen 116 defined by the elongated member 102. Inalternative embodiments, the lumen 116 has any other suitablealternative shape and size and may be eccentrically located through theelongated member 102. In other embodiments that do not comprise thelumen 116, the elongated member 102 is a substantially solid structure.The lumen 116 may be sized to receive the actuator 112 therein, as shownin FIG. 1. For example, in some embodiments, the lumen 116 is largeenough to receive the actuator 112, but is not large enough toaccommodate other wires, sensors, or the passage of fluid. In furtherembodiments, the lumen 116 is sized to receive the actuator 112 alongwith one or more wires but is still not be large enough to accommodatefluid flow. In one specific embodiment, the lumen 116 measures about 0.1mm to about 1.0 mm in diameter. The flexibility of the elongated member102 may be dependent, in part, on the wall thickness of the elongatedmember 102, between an inner diameter defined by the lumen 116 and anouter diameter. In one particular embodiment, the elongated member 102has a wall thickness measuring about 0.01 mm to about 0.2 mm. Theflexibility of the elongated member 102 is also dependant on the outerdiameter of the elongated member 102. In some embodiments, the elongatedmember 102 has a beam strength of at least 0.001 lbf as measured by theASTM E855-90 3-point bent test.

In the embodiment illustrated in FIGS. 1A, 1B and 2, the actuator 112 isoperable to direct at least a portion of the distal end region 104 in adesired direction. In one embodiment, the actuator 112 comprises asingle pull-wire disposed within the lumen 116 of the elongated member102 and attached to at least one point in the distal end region 104 ofthe elongated member 102. For example, the actuator 112 may be attachedto the distal end region 104 at or adjacent to the distal tip 108. Theactuator 112 may be relatively thin, in some embodiments, in order toallow the inner diameter of the elongated member 102 to be reduced, thuspotentially reducing the diameter of the apparatus 100 as a whole. Inone particular embodiment, the actuator 112 measures from about 0.03 mmto about 0.30 mm in diameter.

The actuator 112 may be attached to the elongated member 102 such thatmanipulation of the actuator 112 via the application of mechanicalenergy to transmit tension along the length of the actuator 112 mayeffect a change in the elongated member 102. For example, in someembodiments, manipulation of the actuator 112 may cause at least aportion of the elongated member 102 to change shape. Such a change ofshape may involve the adoption of a bent configuration, wherein, theterm “bent” is defined to mean having a deviation from a straight line;this may take the form of a rigid bend or a subtler curve, with one ormore angles of curvature. In other embodiments, this change of shape mayinvolve a compression, or accordion-like collapsing of the elongatedmember 102, wherein one or more sections of the elongated member 102fold or bend backwards. Such an effect may cause the position of thedistal tip 108 to change, without necessarily inducing any deviation ofthe distal tip 108 away from the longitudinal axis of the distal endregion 104 (i.e. the distal tip 108 may still point in its originaldirection).

In other embodiments of the present invention, the apparatus 100 maycomprise other means for directing at least a portion of the distal endregion 104 in a desired direction. For example, the apparatus 100 maycomprise one or more electro-magnetic, piezoelectric or hydraulicmechanisms for changing the shape of the elongated member 102. In onesuch embodiment, the apparatus 100 may comprise at least onemagnetically responsive element, which may assist in guiding theapparatus 100 to a desired direction upon the application of a magneticfield.

In some embodiments, the apparatus 100 includes a pre-formed curvedsection. In such embodiments, the distal tip 108 may be directed in adesired direction by applying torque to the proximal end region 106. Insuch embodiments, an actuator may not be required.

With respect now to the embodiment shown in FIG. 2, the distal endregion 104 of the elongated member 102 may contain one or more notches200 to aid in a change of shape of the elongated member 102 when tensionis applied through the actuator 112. For the purposes of thisdescription, the notches 200 may be any regions wherein discontinuitiesare present in the wall of the elongated member 102. In someembodiments, the notches 200 comprise scores, cuts, or otherdiscontinuities in either the inner or outer surface of the wall of theelongated member 102 that do not completely traverse the circumferenceof the elongated member 102. In alternative embodiments, the notches 200comprise regions wherein entire sections of the wall of the elongatedmember 102 are absent. In one specific example, as shown in FIG. 2, oneor more sections of the wall of the elongated member 102, each sectionextending at least 180 degrees around the circumference of the elongatedmember 102, are absent, which may result in a toothed or serratedappearance. Notches 200 are present, for example, along about 5 mm toabout 50 mm of the length of the elongated member 102. The notches 200may be regularly or irregularly spaced, identically, similarly ordissimilarly sized, oriented at any angle with respect to the elongatedmember 102 and may lie at any suitable angles along the elongated member102. The notches 200 may have abrupt edges or may comprise regions wherethe thickness of a wall of the elongated member 102 changes gradually tocreate a discontinuity.

In other embodiments, the notches 200 comprise regions composed of amaterial different than that of the surrounding body of the elongatedmember 102. For example, in one embodiment, the elongated member 102 ismade primarily of stainless steel while the notches 200 comprise regionsof the elongated member 102 made of a different material, for example anelastic compound. The notches 200 thus represent discontinuities in thematerial of the wall of the elongated member 102, without necessarilychanging the profile or thickness of the elongated member 102.

The notches 200 may be operable to assist in directing a change in shapeof the elongated member 102 when a force is applied to the elongatedmember 102 through an actuator 112. In one such embodiment as describedabove, the application of tension to the actuator 112 applies a force toan attachment point at the distal tip 108, pulling the attachment pointin a proximal direction. As notches 200 may serve to locally increasethe flexibility of the elongated member 102, the elongated member 102may change shape to, for example, bend preferentially in the directionof the notches 200 when tension is applied. Thus, in some embodiments,the notches 200 may be shaped and positioned around the elongated member102 such that the elongated member 102 will adopt a certain specificcurve or series of curves when tension is applied to the actuator 112.

In some embodiments of the present invention, and referring now to FIG.3A, apparatus 100 includes a handle 300 mechanically coupled to theproximal end region 106 of the elongated member 102. The handle 300 maybe suitable for grasping and manipulating the apparatus 100, for exampleduring insertion, positioning or guiding thereof, and may, in someembodiments, be operable to facilitate a change in shape of theelongated member 102. Referring to FIG. 3B, in some embodiments, thehandle 300 comprises a housing 302, a first securing component 304 and asecond securing component 306. The handle 300 may further comprise ameans for connecting an energy source to one or more of the elongatedmember 102, the actuator 112 and any other electrical conductor operableto deliver energy to the electrode 110. For example, the handle 300 maycomprise an electrical connector for connecting to an energy source. Insuch embodiments, the electrical connector may be coupled to handle the300 via an electrical cable. Alternatively, as shown in FIG. 3B, theactuator 112 may extend from a proximal end of the handle 300 and may beoperable to be electrically coupled to an energy source.

The first securing component 304 may be operable to secure the handle300 to the elongated member 102, while the second securing component 306is operable to secure the handle to the actuator 112. In the embodimentshown in FIGS. 3B to 3D, the second securing component 306 comprises aclamping apparatus operable to securely engage the actuator 112.Actuation of the handle 300 via, for example, a button 310, may effect achange in the relative positions of the first securing component 304 andthe second securing component 306, thus causing the elongated member 102and/or actuator 112 to move with respect to one another. However,actuation of the handle 300 may be achieved using any means fordisplacing a wire or similar component, including but not limited to oneor more of a button, a knob and a switch. Actuation of the handle 300may involve the use of mechanical (including linear, rotational andother forces) and/or electrical energy and may be accomplished remotely.In some embodiments, the handle 300 includes a ratcheting mechanism tomaintain tension in the actuator 112, for example by maintaining theposition of one or more of the first securing component 304 and thesecond securing component 306 following actuation of the handle 300. Insome embodiments, the handle 300 may be removable. For example, in onesuch embodiment, the first and second securing components 304 and 306are each detachable from the elongated member 102 and the actuator 112,respectively. In such embodiments, the handle 300 may further bere-attachable after having been removed. Furthermore, in suchembodiments, the handle 300 may additionally comprise one or more visualmarkers and/or one or more locks or other fastening mechanisms to aid inthe positioning and attachment of the first securing component and thesecond securing component 306 respectively to the elongated member 102and the actuator 112. Such markers and/or locks may be useful to orientthe direction of bending of the elongated member 102 with respect to thehandle 300, and to calibrate the actuator 112 to the amount of tensionalready present in the actuating mechanism. In embodiments comprising anactuator 112 that utilizes means other than tension to direct apparatus100 in a desired direction, the handle 300 may be operable to manipulatethe actuator to effect the desired change in direction.

In accordance with embodiments of the present invention, any portion ofthe elongated member 102, the actuator 112, the notches 200, theelectrode 110 or the insulating material 114 may comprise one or moremarkers. Such markers may include visual markers, tactile markers,radiopaque markers, radiolucent markers, or any other markers used toaid in the visualization, localization, navigation, insertion, ordetection of apparatus 100. Markers may be externally applied to acomponent, and may be of a variety of shapes and structures; they may beraised from the surface of a component or may conform to the surface ofthe component; and they may be internal to a component. In someembodiments, components may be manufactured in whole or in part frommaterials that provide a visual or tactile distinction, thus actingthemselves as markers. For example, in one embodiment, the insulatingmaterial 114 is manufactured from a radiopaque insulating material orfrom a material comprising radiopaque fillers. In another embodiment,one or more of the elongated member 102, the distal tip 108, theelectrode 110 and the actuator 112 are plated with a radiopaquematerial, such as platinum or tungsten. In yet another embodiment, aradiopaque marker, such as a band, is welded or otherwise attached to,for example, the distal tip 108 or the electrode 110.

In some embodiments, as mentioned hereinabove, any or all of the lumen116, the actuator 112 and the notches 200 may not be present in theapparatus, in order, for example, to simplify the process ofmanufacturing the apparatus 100 and make it more cost-effective. Inaddition, in such embodiments, the apparatus 100 may have substantiallysimilar mechanical properties when compared to a standard mechanicalguide-wire.

In some embodiments of the present invention, the apparatus 100 furthercomprises one or more means for guiding the apparatus 100 within thebody of the patient. For example, in one particular embodiment, theapparatus 100 further comprises an ultrasound transducer (not shown inthe drawings) associated with the distal end region 104. The ultrasoundtransducer (not shown in the drawings) may be operable as anintra-vascular ultrasound (IVUS) device, which may assist in determiningthe position of the apparatus 100 within a blood vessel, for example. Insuch an embodiment, the ultrasound transducer (not shown in thedrawings) may be electrically connected to an ultrasound generator, forexample via one or both of the elongated member 102 and the actuator112. In another specific embodiment, the apparatus 100 further comprisesat least one optical fiber (not shown in the drawings) which may beoptically coupled to an optical coherence reflectometry (OCR) system(not shown in the drawings), which may also assist in determining theposition of the apparatus 100 within a blood vessel, for example.Another example of a suitable device or apparatus is described inapplication Ser. No. 12/926,292, which is incorporated herein byreference in its entirety.

Materials

In embodiments wherein the elongated member 102 takes the form orincludes an electrically conductive core wire, as described hereinabove,it may be made of a biocompatible metal or metal alloy, for example,including, but not limited to, stainless steel or nitinol. The actuator112 may be conductive, and may, in some embodiments, have a high tensilestrength, thus being able to tolerate the application of sufficientforce to cause a change in shape of the elongated member 102, when aforce is applied to the actuator 112. An example of a material that issuitable for the actuator 112 is nitinol. The insulating material 114may be composed from any material capable of providing electricalinsulation, including, in some embodiments, Parylene orpolytetrofluoroethylene (PTFE). The insulating material 114 may beapplied to the elongated member 102 by a variety of methods including,but not limited to: being overlain onto the elongated member 102 andshrunk by the application of heat, being extruded over the elongatedmember 102, and being sprayed or painted onto the elongated member 102in liquid form. Suitable materials for radiopaque markers or componentsinclude, but are not limited to, high-density metals such as platinum,iridium, gold, silver, tantalum, and tungsten or their alloys, orradiopaque polymeric compounds. Although the above materials aresuggested as being suitable options for the manufacture of components ofthe present invention, the list is by no means meant to be limiting, andany other components with suitable properties may be used.

Method

In some embodiments, the apparatus 100 is usable to create a channel ina foreign material located the body of a patient (not shown in thedrawings). This channel may be created, in some embodiments, at leastpartially by the delivery of energy using the electrode 110. Morespecifically, the electrode 110 is energized with a radiofrequencycurrent and the electrode 110 is then used to deliver energy into theforeign material to create the channel. In some embodiments, the energydelivered in the foreign material is thermal energy.

Without being limited to a particular theory of operation, it ishypothesized that, in some embodiments, the proposed method is performedwhen the electrode 110, which is energized with a radiofrequencycurrent, heats up to a predetermined temperature. For example, thepredetermined temperature may be substantially larger than a meltingtemperature of the foreign material. Then, thermal energy is transferredfrom the electrode 110 to the foreign material to substantially melt theforeign material adjacent to the electrode 110, thereby creating achannel through the foreign material. In other embodiments, it ishypothesized that water may be absorbed by the foreign material, andradiofrequency energy that is thereafter delivered to the foreignmaterial may cause vaporization of the water adjacent to the electrode110, thereby creating a channel through the foreign material.

In some embodiments, heating of the electrode 110 is performed while theelectrode 110 is positioned at a predetermined distance from the foreignmaterial and from biological tissues adjacent to the foreign material.Positioning the electrode at a predetermined distance from the foreignmaterial and from the biological tissues adjacent to the foreignmaterial minimizes risks of injuring the biological tissues adjacent tothe foreign material. For example, the predetermined distance is suchthat thermal energy transfer between the electrode 110 and either orboth of the foreign material and biological tissues adjacent to theforeign material results in a non-damaging increase in temperaturethereof. As mentioned hereinabove, the use of a radiofrequency currentto heat the electrode 110 helps in minimizing this heat transfer, andtherefore contributes to the practicality of the proposed method as thepredetermined distance is then relatively small.

Minimizing injuries to tissues is of paramount importance whenperforming interventions in patients. Indeed, injuring a tissuetypically creates stress and inflammatory responses that may causeirreversible damages to many tissues. In addition, many patients have arelatively sensitive hypothalamic-pituitary-adrenal axis (HPA axis) andlocal stresses to tissues can lead in these patients to systemic andpsychiatric conditions and diseases. In some embodiments, the proposedmethod is performed in the heart of the patient. In these cases, theseirreversible damages can lead to dysfunctions in the contractile andelectrical conductivity properties of the cardiac tissue, whichthemselves can lead to life-threatening conditions.

It is hypothesized that providing the radiofrequency current to theelectrode 110 within the body creates a layer of water vapor around theelectrode 110, which reduces thermal transfer between the electrode 110and adjacent structures that are sufficiently spaced apart therefrom.This helps in ensuring a relatively fast heating of the electrode 110and reduce risks of damaging biological tissues as describedhereinabove.

In such embodiments, the electrode 110 is then moved so as to besubstantially adjacent to the foreign material. As the electrode has nowattained a temperature substantially higher than the melting temperatureof the foreign material, the electrode effectively melts the foreignmaterial to create a channel therethrough.

However, in alternative embodiments of the invention, positioning of theelectrode 110 substantially adjacent to the foreign material, forexample to a first surface of the foreign material, is performed beforeenergizing the electrode 110.

Generally speaking, the aforementioned specifics of the proposed methodare typically part of a treatment procedure comprising the steps of:providing the apparatus 100, or any other suitable apparatus; insertingat least a portion of the apparatus 100 into the body of the patient,for example by introducing the distal end region into the body of thepatient; positioning the electrode 110 substantially adjacent to thematerial first surface; energizing the electrode 110 with aradiofrequency current; and using the electrode 110 energized with theradiofrequency current to deliver energy into the foreign material tocreate the channel. Further embodiments may comprise additional stepsof, for example, manipulating an actuator, or otherwise guiding theapparatus 100 through one or more of the body vasculature of the patientand the channel.

In accordance with embodiments of the treatment method aspects of thepresent invention, the apparatus 100 may be a component of a systemincluding an energy source (not shown in the drawings) (such as, forexample, the RFP-100 or RFP-200 Baylis Medical RF Puncture Generators,manufactured by Baylis Medical Company Inc., Montreal, Canada), and agrounding pad (not shown in the drawings) or any other return electrode,if operated in a monopolar mode.

FIG. 4 illustrates, in a flow-chart form, one embodiment of a method 400in accordance with the present invention. This embodiment comprises: atstep 402, preparing a patient and a system for treatment; at step 404,inserting a portion of the apparatus 100, into the body vasculature ofthe patient; at step 406, navigating the apparatus 100 through the bodyvasculature to a target site; at step 408, changing a of shape, orotherwise reorienting the apparatus 100 in order to position theelectrode 110, or any other suitable electrode, adjacent at least aportion of the foreign material; at step 410, confirming or otherwiseassessing the position of the electrode 110; at step 412, deliveringenergy via the apparatus 100 to create a channel in the foreignmaterial; at step 414, advancing the apparatus 100, for example thedistal end region 104 and the electrode 110, through the channel; atstep 416, assessing the position of the electrode 110 or any otherportion of the apparatus 100 after it has been advanced through thechannel; and, at step 418, performing an additional procedure at oraround the target site. The reader skilled in the art will readilyappreciate that the patient may be a human or an animal and that one ormore of these steps may not necessarily be performed in a givenprocedure or that one or more of these steps may be performed in adifferent order, as will be further clarified hereinbelow.

In step 402, preparing a patient for treatment may include, but is notlimited to one or more of: visualizing one or more treatment siteswithin the body of the patient using fluoroscopy, x-ray, contrast media,labeled markers such as radioactive compounds or solutions, usingendoscopy procedures, using ultrasound, using Doppler imaging, or anyother visualization method; characterizing the vascular system of thepatient by measuring blood or serum levels of various compounds;measuring vascular pressure; and undertaking any other measuring ormonitoring technique that may provide information that may be usefulduring any other step of the method. In step 402, preparing a system fortreatment may include, but is not limited to one or more of: connectinga treatment apparatus, for example the apparatus 100 as described above,to an energy source; connecting a grounding pad or other returnelectrode to the energy source; placing the grounding pad or returnelectrode on the body of the patient; passing the actuator 112 throughthe elongated member 102 (in some embodiments, the actuator 112 may bepermanently threaded through the elongated member 102, thus obviatingthis step), if the apparatus 100 comprises the actuator 112; securingthe handle 300 to the actuator 112 and the elongated member 102 (in someembodiments, the handle 300 may be permanently connected to theelongated member 102 and the actuator 112, thus obviating this step);and attaching one or more additional components to the apparatus 100. Asmentioned above, one or more of these steps may not be performed in aparticular procedure, depending on the apparatus 100 being used and thespecific procedure being performed.

The step 404 of inserting the apparatus 100 into the body vasculature ofthe patient may comprise percutaneously inserting the apparatus 100 intoa blood vessel of the body vasculature through which the apparatus maybe navigated to the target site. For example, in some embodiments, theapparatus 100 may be inserted into a femoral artery or vein or asubclavian artery or vein. The apparatus may be inserted directly intothe blood vessel or may be inserted through a guiding catheter orsheath.

The step 406 of navigating the apparatus 100 through the bodyvasculature to a target site may involve advancing the apparatus 100through the body vasculature to the target site. In some specificembodiments, in which the apparatus is inserted through a guiding sheathor catheter, the sheath or catheter may initially be navigated to thetarget site, for example by initially inserting a guidewire to thetarget site and then tracking the sheath/catheter over the guidewire.Once the sheath/catheter is in place, the guidewire may be removed andthe apparatus 100 may be inserted through the sheath/catheter. Step 406may additionally involve any of a variety of visualization techniques,including those techniques mentioned above for visualizing one or moretreatment sites within the body of the patient. In one embodiment, theapparatus 100 may be furnished with one or more radiopaque markers,which may aid in the visualization of the apparatus 100.

The step 408 of affecting a change of shape in the apparatus 100 may berequired, for example if the step of navigating the apparatus 100 doesnot position the apparatus 100 sufficiently precisely. This step is, insome embodiments, accomplished by effecting a change of shape in thedistal end region 104 of the elongated member 102, as describedhereinabove. In some embodiments, it may be desirable to approach theforeign material substantially perpendicularly, for example at an angleof about 80 degrees to about 100 degrees, and step 408 is usable tocontrol this angle.

The step 410 of confirming a position of the apparatus 100 may involvevisualizing the position of one or more portions of the apparatus 100within the body of the patient. For example, radiopaque markers includedin the apparatus 100 may be visualized using fluoroscopy. Alternatively,or in addition, radiopaque contrast may be injected, for example throughthe guiding sheath/catheter, in order to confirm the position of theapparatus 100. Furthermore, in some embodiments, the apparatus 100 mayinclude a pressure sensor (not shown in the drawings) operativelycoupled to the distal end region of the apparatus for measuring apressure at or around the distal end of the apparatus. In suchembodiments, blood pressure may be reassured in order to confirm theposition of the apparatus.

The step 412 of delivering energy may include an optional step ofmeasuring, assessing or sensing the composition of the foreign materialto be penetrated. For example, in one embodiment, the apparatus 100 maybe used as part of an impedance monitor to determine the impedance ofthe material to be penetrated. The impedance value thus measured maythen be compared to known impedance values of various materials in orderto determine the composition of the material to be penetrated. Then,energizing the electrode 110 is performed, in some embodiments, at leastin part, in a manner depending on the composition of the foreignmaterial. For example, the electrode 110 may be energized at variouspower levels, depending on the nature of the foreign material.Alternatively, a change in impedance may indicate that the material incontact with the apparatus has changed. For example, a lower impedancemay indicate that the apparatus is in contact with a metallic orotherwise conductive portion of a stent or scaffold, as opposed to thegraft material associated with the stent/scaffold. In such a situation,a user may reposition the apparatus until a suitable impedancemeasurement is recorded indicating that the apparatus is substantiallyadjacent to the foreign material through which the channel is to becreated.

Alternatively, tactile feedback may be used to assist in determining thematerial in contact with the apparatus. For example, a user may usetactile feedback to determine whether the apparatus is in contact withmetallic material of a stent/scaffold or more flexible graft material,through which a channel may be created. Alternatively, or in addition,imaging techniques (for example OCR and/or IVUS) may be used todetermine the composition of material in contact with the apparatus 100.As described hereinabove, the composition of the material to bepenetrated may determine the initial parameters of energy delivery.

The step 412 of delivering energy via the apparatus 100 to create achannel in the foreign material comprises, in one embodiment, deliveringelectromagnetic energy (for example electric energy in theradiofrequency (RF) range) to the electrode 110. In one specificembodiment, the RF current provided may have a frequency in the range offrom about 300 kHz to about 1 MHz, and more specifically, in veryspecific embodiments of the invention, of from about 460 kHz to about500 kHz, and may be delivered with a power of at least about 5 W at avoltage of at least about 75 Volts (peak-to-peak).

In some embodiments, one or more parameters may be measuredsubstantially while energy is being delivered and/or the device is beingadvanced. For example, impedance may be measured substantiallycontinuously or at predetermined intervals during energy delivery and/oradvancement of the apparatus and a change in impedance may lead to achange in energy delivery. In one particular example, a drop inimpedance may indicate that the apparatus is contacting a metallicportion of a stent/scaffold and energy delivery may be stopped so thatthe device may be repositioned. The change in energy delivery may beautomatic or may be manually performed by the user.

In some embodiments of the invention, the energy may be delivered for apredetermined amount of time before stopping the delivery of the energy.In other embodiments, the intended user may decide, during the course ofthe procedure, on the amount of time during which energy should bedelivered. The intended user's decision may depend, for example, on oneor more of tactile feedback, impedance measurements, pressuremeasurements, predetermined information regarding the material beingpenetrated (e.g. the thickness of the material) or the preferences ofthe intended user. In one example, if a user feels that the device haspenetrated through the foreign material he may stop delivering energy.In some embodiments, the amount of time during which energy is deliveredis from about 0.1 seconds to about 5 seconds. In a more specificembodiment of the invention, the amount of time during which energy isdelivered is from about 1 second to about 2 seconds. During theseperiods of time, the energy may be delivered continuously or as a pulsedwaveform.

The step 414 of advancing the apparatus through the channel may compriseapplying a longitudinal force to the proximal end region 106 of theapparatus 100 in order to advance the distal end region 104 of theapparatus 100 through the channel. Alternatively, mechanical or magneticmeans for advancing the apparatus may be used. In some embodiments, step414 occurs at least partially concurrently with step 412, such that theapparatus is advanced while energy is being delivered.

Following step 414, the position of the apparatus 100, after passingthrough the channel, may be confirmed at step 416. Step 416 may beperformed in substantially the same manner as step 410, describedhereinabove.

The step 418 of performing another treatment procedure may involve, insome embodiments, one or more of: introducing a balloon catheter, adilator or other means for dilation of the channel, to the target site,for example overtop of or through the apparatus 100; introducing a stentor other supporting structure to the target site, for example overtop ofor through the apparatus 100; delivering a pharmaceutical compound tothe target site; delivering energy to create a lesion or coagulatetissue or fluid in the vicinity of the target site; introducing emboliccoils; placing an IVUS or OCR probe for visualization; or adding orremoving any other material to or from the site. In addition, this stepmay further comprise removal and possible re-attachment of the handle300 of the apparatus 100, in order to allow for the introduction ofanother device to the treatment site. As mentioned hereinabove, inalternative embodiments of the invention, the electrode 110 is energizedafter having been positioned adjacent to the foreign material.

Embodiments of the treatment procedure described above may beparticularly useful to create a channel through material of a stentgraft occluding one or more vessels of a patient's body. Severalexamples of such applications are noted hereinbelow. While theseexamples have been described in specific detail, one of skill in the artwill appreciate that embodiments of the present invention may beutilized in various other procedures and applications.

EXAMPLES Example 1

In a first example, an embodiment of a proposed method is used to createa channel 512, seen in FIG. 5B, within a septal patch 510 made offoreign material, the septal patch 510 defining a material first surface514 and a substantially opposed material second surface 516. The channel512 extends between the material first and second surfaces 514 and 516.The septal patch 510 extends across an aperture 518 defined by theseptum 520 of the heart 500 of the patient, for example an atrial septumor a ventricular septum. For example, the septal patch 510 covers theaperture and extends in a plane outside of the septum 520. In otherexamples, the septal patch 510 extends inside the aperture 518. Some ofthese procedures may involve patients that have had a septal defectrepaired with the septal patch 510. In some cases, such patients maysuffer from one or more conditions which require access to the left sideof the heart for treatment to be performed. In such situations, accessto the left side of the heart may be gained by creating the channel 512in the septal patch 510. In such embodiments, the septal patch 510 maybe made of a foreign material selected from the group consisting ofpolyethylene terephthalate (PET, for example Dacron®), cotton, apolyester material and fabrics thereof.

With reference to FIG. 5A, the apparatus 100 is inserted through theinferior vena cava 502 into the right atrium 506 of the heart 500. Inalternative embodiments, access to the right atrium may be achieved viathe superior vena cava 504 as described, for example, in co-pending U.S.patent application Ser. No. 11/265,304 (Filed on Nov. 3, 2005), which isincorporated herein by reference in its entirety. FIG. 5A shows theapparatus 100 positioned in the right atrium 506 with the electrode 110located substantially adjacent the material first surface 514. FIG. 5Bshows the apparatus 100 positioned in the left atrium 508 after beingadvanced through the channel 512. In this particular embodiment,radiofrequency energy may be delivered, for example, at about 5 W for aperiod of less than about 5 seconds.

In a further example application, an embodiment of a method according tothe present invention may be useful, for example, to create a channelwithin a graft composed of foreign material. In some embodiments, thegraft is associated with a substantially tubular supporting structure,for example a stent, located within an elongated vessel of the body ofthe patient. In some such embodiments, the method is performed in orderto restore blood flow to a branch of the elongated vessel being occludedby the graft material, thus substantially preventing fluid communicationbetween the branch and the elongated vessel, by creating a channelthrough the material.

With reference now to FIGS. 6A, 6B, 7A and 7B, methods for in-situcreation of a channel through a stent-graft are illustrated. In theillustrated embodiments, a stent-graft 606, composed of a foreignmaterial, has been placed to cover an aneurysm 604 in an abdominal aorta600. As shown in these figures, stent-graft 606 occludes the renalarteries ostia 605.

This positioning of the stent-graft 606 is typically necessitated by aninadequate, i.e. too short, proximal neck of the abdominal aorta 600.One of the greatest challenges of stent-grafting an abdominal aorticaneurysms 604 is to obtain a long proximal attachment site to ensure agood seal without occluding the renal or supra-aortic vessels. If a longproximal site is unavailable, the ostia of the renal and/or supra-aorticvessels may become occluded by the stent-graft 606. The presentinvention provides a method for creating a transluminal in-situ channelin order to restore blood flow to any vessels that do become occludedduring the course of such a procedure.

Example 2

With reference first to FIGS. 6A and 6B, an antegrade approach toin-situ channel creation is provided. In this approach, the distal endregion 104 is introduced into the body of the patient through the bodyvasculature inside the thoracic cavity, or in other words from aposition superior to the diaphragm of the patient, and advanced towardsthe abdominal aorta 600 in which the electrode 110 is then positioned.FIG. 6A shows the electrode 110 of the apparatus 100 positioned in theabdominal aorta 600 substantially opposite the renal artery ostium 605,which is occluded by the stent-graft 606. At this point, energy may bedelivered from an energy source through the electrode 110 in order tocreate a channel 608, as seen in FIG. 6B, in or through the stent-graft606. FIG. 6B shows the electrode 110 after it has been advanced throughthe channel 608 into the renal artery 602. Creation of the channelallows for fluid communication and restoration of blood flow between theabdominal aorta 600 and the renal artery 602. At this point, asdescribed above with respect to FIG. 4, the channel 608 may be dilatedusing one or more of a dilator and a balloon (for example a cuttingballoon) and a stent may be placed across the channel 608 to maintainthe patency of the renal artery 602.

With reference now to FIGS. 7A and 7B, a retrograde approach isillustrated. In this approach, introducing the distal end region 104into the body of the patient includes introducing the distal end regioninto the body vasculature and through the renal artery 602 towards theabdominal aorta 600. In such an embodiment, positioning the electrode110 substantially adjacent to a material first surface then includespositioning the electrode 110 substantially adjacent to the renal arteryostium 605 outside of the abdominal aorta 600.

With reference first to FIG. 7A, the electrode 110 of the apparatus 100is positioned in the renal artery 602 at the renal artery ostium 605,which is occluded by the stent-graft 606. At this point, energy may bedelivered from an energy source through the electrode 110 in order tocreate a channel 608 in or through the stent-graft 606. FIG. 7B showsthe electrode 110 after it has been advanced through the channel 608into the abdominal aorta 600. As mentioned hereinabove, creation of thechannel 608 may allow for fluid communication and the restoration ofblood flow between the abdominal aorta 600 and the renal artery 602. Atthis point, as described above with respect to FIG. 4, the channel 608may be dilated using one or more of a dilator and a balloon (for examplea cutting balloon) and a stent may be placed across the channel tomaintain the potency of the renal artery. It should be noted that in theembodiment of FIGS. 7A and 7B, step 404 of the method comprisesobtaining access to renal artery 602, for example during a surgicalprocedure or via a deep puncture.

It should be noted that, although this example has been described inconjunction with treatment of an abdominal aortic aneurysm, a similarmethod is also contemplated for treating a thoracic aortic aneurysm,whereby a subclavian artery, for example, may become occluded by astent-graft. Such a condition may be more easily treated using aretrograde approach, by inserting an apparatus through the subclavianartery towards the aorta. In addition, vessels other than the renalarteries 602 may be occluded by an abdominal aortic stent-graft, forexample the mesenteric arteries (not shown in the drawings).Alternatively, similar embodiments of the method may be practiced inother situations whereby a vessel ostium (or any portion of an elongatedvessel, tube and/or duct) in a patient's body is occluded by a foreignmaterial.

Example 3

With reference now to FIGS. 8A-8D, alternate methods for in-situcreation of a channel through a stent-graft are illustrated. In theillustrated embodiments, a stent-graft 806, composed of a foreignmaterial, has been placed to cover an aneurysm 804 in a section of thedescending aorta, more specifically, within the thoracic aorta 800. Asshown in these figures, the stent-graft 806 occludes the opening orostium 805 of the Left Subclavian Artery (LSA) 802.

In the illustrated example, the positioning of the stent-graft 806 atthe LSA ostium 805 is necessitated by the proximity of the LSA ostium805 to the site of the aneurysm 804. A challenge is generally presentedwhen an aneurysm 804 occurs within a vessel near an ostium of a sidebranch vessel, such as the LSA 802. It may become difficult to place thestent-graft 806 within the vessel to ensure protection of the aneurysm804 while maintaining patency of the side branch ostium. In one suchexample, the aneurysm 804 and the LSA ostium 805 are locatedsubstantially adjacent each other. “Adjacent” may be taken to mean nextto, in proximity to, near to, or in the vicinity of. In one example theaneurysm 804 and the LSA ostium 805 are located opposite to one anotheralong the coronal and/or saggital planes. In other words, the aneurysm804 and the LSA ostium 805 are radially opposed to one another. In afurther example, the aneurysm 804 and the ostium 805 may be positionedaxially adjacent to one another. In other words, the aneurysm 804 andthe LSA ostium 805 may be positioned substantially collinearly withrespect to each other. Thus, the proximity of the aneurysm 804 to theLSA ostium may necessitate the positioning of the stent-graft 806 suchthat it covers the aneurysm 804 but also occludes the LSA ostium. Thispositioning of the stent-graft 806 is typically necessitated by aninadequate, i.e. too short, proximal neck of the thoracic aorta 800. Oneof the greatest challenges of stent-grafting a thoracic aortic anerurysm804 is to obtain a long proximal attachment site to ensure a good sealwithout occluding any of the side branch vessels such as the LeftSubclavian Artery (LSA) 802, the Right Subclavian Artery (RSA) 808, LeftCommon Carotid Artery (LCCA) 810 or Right Common Carotid Artery (RCCA)812. If a long proximal site is unavailable, then an ostium of a sidebranch vessel may become occluded by the stent-graft 806. For thespecific case shown in FIGS. 8A-8D, to treat a thoracic aortic aneurysm,the LSA ostium may become occluded by the stent-graft 806. Thisillustrated embodiment of the present invention provides a method forcreating a transluminal in-situ channel in order to restore blood flowto any vessels that do become occluded during the course of such aprocedure.

With reference first to FIGS. 8B, and 8C, a retrograde approach toin-situ channel creation is illustrated. In this approach, introducingthe distal end region 104 of apparatus 100 into the body of the patientincludes introducing the distal end region 104 into the body vasculatureand through the left subclavian artery (LSA) 802 towards the thoracicaorta 800. In one specific example, a guide sheath 900 is introducedinto the body of the patient through the body vasculature and advancedinto the LSA via the left brachial artery. The sheath 900 is advancedtill a distal end of the sheath 900 is located about 5 cm from thestent-graft 806. The apparatus 100 according to an embodiment of thepresent invention, along with a guide catheter (not shown), is then beinserted through the guide sheath 900. The distal end region 104 ofapparatus 100 is then advanced towards the LSA such that the electrode110 is positioned adjacent the stent-graft 806 that is occluding the LSAostium 805. In such an embodiment, positioning the electrode 110substantially adjacent to a material first surface includes positioningthe electrode 110 substantially adjacent to the LSA ostium 805 outsideof the thoracic aorta 800. In some embodiments, a curved guide catheteror a centering mechanism may be used to direct the apparatus 100 towardsthe center of the LSA to position electrode 110 at the desired targetlocation. In one example, a balloon catheter may be used to centre theapparatus 100 within the vessel.

When creating a channel through a stent-draft such as stent-graft 806, astrut 807 of the stent forming the stent-graft 806 may obstructadvancement of apparatus 100 through the stent-graft 806. In someembodiments of the present invention, a guide catheter is used to directthe apparatus 100 around the strut 807, as follows: The guide catheterand apparatus 100 may be aligned with the stent such that they arepositioned against the strut 807. Gentle buckling of thecatheter/apparatus assembly may be used to confirm that thecatheter/apparatus assembly is positioned against the stent. The guidecatheter may be incrementally adjusted around the strut 807 such that itis no-longer blocked by the strut 807. In some embodiments, a RightAnterior Oblique (RAO) view under fluoroscopic imaging may be used toguide the catheter and the apparatus 100 to the appropriate position.

Once the electrode is positioned appropriately, energy is deliveredthrough the electrode 110 to puncture through the graft to create achannel 808 there-through. In some embodiments, the energy may beapplied at a voltage of about 400 Vrms, with a duty cycle of 25 msON/975 ms OFF. In one particular example, energy is applied using theBaylis RFP-200 Generator at a high power setting for 2 seconds topuncture the graft/fabric of the stent-graft. In another example, it maybe sufficient to deliver energy twice at durations of 1 second. Theapparatus 100 may then be advanced into the stent-graft 806 underfluoroscopic guidance. In some embodiments, the energy may be deliveredwith the power being in the range of between about 30 Watts to about a100 Watts; and the voltage may be in the range of between about 300 Vrmsto about 500 Vrms. In some embodiments the energy may be applied forduration of at least 25 ms. Furthermore, in some embodiment the ONperiod of the duty cycle may range from between about 25 ms to about1000 ms.

FIG. 8D shows the electrode 110 after it has been advanced through thechannel 808 into the thoracic aorta 800. As mentioned hereinabove,creation of the channel 808 may allow for fluid communication and therestoration of blood flow between the thoracic aorta 800 and the LSA802. At this point, as described above with respect to FIG. 4, thechannel 808 may be dilated using one or more of a dilator and a balloon(for example a cutting balloon) and a stent may be placed across thechannel to maintain the patency of the LSA. It should be noted that inthe embodiment of FIGS. 8B and 8C, step 404 of the method comprisesobtaining access to LSA 802, for example during a surgical procedure orvia a deep puncture.

An additional challenge that may be faced when creating a channelthrough a stent-graft using radiofrequency energy is contact of theenergized electrode with a strut, for example strut 807, of thestent-graft 806. Embodiments of the present invention provide a methodfor indicating a metal contact error if the electrode 110 of theapparatus 100 is in contact with the strut 807. In accordance with suchembodiments, the energy delivery system prevents delivery of energy whenthe electrode 110 is positioned adjacent to or in contact with themetallic strut 807 but allows the apparatus 100 to delivery energy nearthe electrically conductive strut 807 of the stent-graft 806. Thisallows the physician to continue to deliver energy from the electrode110 and steer the electrode 110 away from the strut 807. Thus, theorientation or position of the electrode 110 may be re-adjusted bymoving it around or away from the metal strut 807, while power is beingdelivered. This allows the user to deliver energy from electrode 110while it is positioned close to the metallic strut 807, allowingelectrode 110 to cut through the stent-graft 806, but generating a“metal detect” error if the electrode 110 is in contact with themetallic strut 807 or close enough to produce undesired arcing.

With reference first to FIGS. 9A and 9B, an antegrade approach toin-situ channel creation is provided. In this approach, the distal endregion 104 is introduced into the body of the patient through the bodyvasculature and advanced towards the thoracic aorta 800 in which theelectrode 110 is then positioned. In one specific example, femoralaccess is used to guide the distal end region 104 of the apparatus 100into the lumen of the stent-graft 806 that is positioned within thethoracic aorta. FIG. 9A shows the electrode 110 of the apparatus 100positioned in the thoracic aorta 800 substantially opposite the leftsubclavian artery (LSA) ostium 805, which is occluded by the stent-graft806. At this point, energy may be delivered from an energy sourcethrough the electrode 110 in order to create a channel 808, as seen inFIG. 9B, in or through the stent-graft 806. FIG. 9B shows the electrode110 after it has been advanced through the channel 808 into the leftsubclavian artery (LSA) 802. Creation of the channel allows for fluidcommunication and restoration of blood flow between the thoracic aorta800 and the LSA 802. At this point, as described above with respect toFIG. 4, the channel 808 may be dilated using one or more of a dilatorand a balloon (for example a cutting balloon) and a stent may be placedacross the channel 808 to maintain the patency of the LSA 802.

FIG. 10 is a flow chart illustrating an example of such a method. Asshown by step 1004, an energy delivery device such as apparatus 100 maybe positioned within a region of tissue at a target location within apatient's body. At step 1006, an RF power source may be used to supplyRF energy to the apparatus 100. An energy delivery parameter, forexample the current output from the ground return pathway of theapparatus 100, is monitored. The measured values of the current arecompared to a predetermined current range or magnitude threshold.

At step 1008, the measured current is analyzed to determine if it isgreater than the predetermined threshold or range. If the current haspeak currents that exceed the current magnitude threshold or normaloperational currents, at step 1010 an excess current or over-current isrecorded. If the monitored current is within the range of normaloperational currents (below the predetermined current threshold), thenthe delivery of energy through the energy delivery device will not beinterrupted and energy delivery can continue at step 906 and the currentcan continue to be monitored. At step 1012, a determination is made toassess whether or not the extent of over-currents recorded within a timeperiod is greater than a predetermined sensitivity threshold and, if itis, then the energy delivery may be adjusted at step 1014. In oneexample, adjustment of the energy delivery comprises stopping thedelivery of energy. In some embodiments, the extent of over-currentsrecorded may be determined in terms of the sum or magnitude of theover-currents recorded. In other embodiments, the extent ofover-currents recorded may be determined in terms of the number orquantity of over-currents recorded. If the extent of over-currents isbelow the sensitivity threshold, then at step 1006 the energy deliveryis continued while monitoring the current. Such a method as describedabove can thereby be utilized to prevent delivery of energy to theelectrode when it would be detrimental to the patient to do so, forexample when the electrode is positioned too close to a strut of thestent graft. Further details regarding the generation of a “metaldetect” error as described hereinabove are found in U.S. provisionalapplication No. 60/827,446, previously incorporated herein by reference.

A method for transluminal in-situ channel formation, for example asdescribed herein, allows for more accurate placement of the channel,less reliance on preoperative imaging, increased availability anddecreased cost of a “universal”, non-customized graft, and eventually,more accessibility for a greater number of patients to the advantages ofendovascular repair. As well, the technique could be used as a ‘salvage’procedure when inadvertent coverage of side branches occurs. Mostimportantly, it would allow more accurate placement of the channels withthe stent-graft in place in the aorta, rather than based on preoperativeradiographic imaging.

The methods of the present invention provide a surprising and unexpectedresult in that energy, for example radiofrequency electrical energy isusable to create a channel in foreign material within the body of thepatient, including, for example, synthetic material substantially notcomposed of cellular-based biological tissue (although it may, in someembodiments, be covered with live cells if, for example, it has beenimplanted in the body for a sufficient amount of time). In addition,embodiments of the present invention may minimize the risk of accidentalpuncture or perforation of a blood vessel or other bodily structure.Furthermore, embodiments of the present invention provide for thecreation of a channel without requiring a mechanical tear of the foreignmaterial. The methods of the present invention may also be useful inother applications, including, in general, wherever foreign material ina patient's body should be penetrated.

Many other methods and particular applications may be used with anapparatus of the present invention, and some embodiments of the methodof the present invention may be used with an apparatus other than thatspecifically described in the “APPARATUS” section of this application.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the present invention has been described hereinabove by way ofpreferred embodiments thereof, it can be modified, without departingfrom the scope and nature of the subject invention as defined in theappended claims.

What is claimed is:
 1. A method for creating a channel through a foreignmaterial located in a body of a patient, said foreign material defininga material first surface and a substantially opposed material secondsurface, said channel extending through said foreign material betweensaid material first and second surfaces, said method using an apparatusincluding an electrode, said method comprising: positioning saidelectrode substantially adjacent to said material first surface;energizing said electrode with a radiofrequency current; and using saidelectrode energized with said radiofrequency current to deliver energyinto said foreign material to create said channel; wherein said foreignmaterial is included in a stent graft.
 2. A method as defined in claim1, wherein said positioning of said electrode substantially adjacent tosaid material first surface is performed before energizing saidelectrode.
 3. A method as defined in claim 1, further comprisingadvancing said electrode into said foreign material towards saidmaterial second surface while delivering said energy into said foreignmaterial.
 4. A method as defined in claim 1, wherein said foreignmaterial includes a synthetic material.
 5. A method as defined in claim1, wherein said foreign material includes a material selected from thegroup consisting of polyethylene terephthalate (PET), cotton, apolyester material and fabrics thereof.
 6. A method as defined in claim1, further comprising delivering said energy into said foreign materialfor a predetermined duration; and stopping delivery of said energy intosaid foreign material after said predetermined duration.
 7. A method asdefined in claim 6, wherein said predetermined duration is from about0.1 second to about 5 seconds.
 8. A method as defined in claim 7,wherein said predetermined duration is from about 1 second to about 2seconds.
 9. A method as defined in claim 1, further comprising dilatingsaid channel.
 10. A method as defined in claim 1, wherein said body ofsaid patient includes a body vasculature having a first vessel and asecond vessel branching off of the first vessel; and said foreignmaterial is included in a stent graft located within said first vesseland occluding an opening of said second vessel.
 11. A method as definedin claim 10, wherein said first vessel comprises an abdominal aorta andsaid second vessel comprises a renal artery branching from saidabdominal aorta at a renal artery ostium; said stent graft occludes saidrenal artery ostium; positioning said electrode substantially adjacentto said material first surface includes positioning said electrodesubstantially adjacent to said renal artery ostium outside of saidabdominal aorta; and using said electrode energized with saidradiofrequency current to deliver said energy into said foreign materialto create said channel includes delivering said energy into said stentgraft.
 12. A method as defined in claim 10, wherein said first vesselcomprises an abdominal aorta and said second vessel comprises a renalartery branching from said abdominal aorta at a renal artery ostium;said stent graft occludes said renal artery ostium; positioning saidelectrode substantially adjacent to said material first surface includespositioning said electrode substantially adjacent to said renal arteryostium inside of said abdominal aorta; and using said electrodeenergized with said radiofrequency current to deliver said energy intosaid foreign material to create said channel includes delivering saidenergy into said stent graft.
 13. A method as defined in claim 10,wherein said first vessel comprises a thoracic aorta and said secondvessel comprises a left subclavian artery branching from said thoracicaorta at a left subclavian artery ostium; said stent graft occludes saidleft subclavian artery ostium; positioning said electrode substantiallyadjacent to said material first surface includes positioning saidelectrode substantially adjacent to said left subclavian artery ostiumoutside of said thoracic aorta; and using said electrode energized withsaid radiofrequency current to deliver said energy into said foreignmaterial to create said channel includes delivering said energy intosaid stent graft.
 14. A method as defined in claim 10, wherein saidfirst vessel comprises a thoracic aorta and second vessel comprises aleft subclavian artery branching from said thoracic aorta at a leftsubclavian artery ostium; said stent graft occludes said left subclavianartery ostium; positioning said electrode substantially adjacent to saidmaterial first surface includes positioning said electrode substantiallyadjacent to said left subclavian artery ostium inside of said thoracicaorta; and using said electrode energized with said radiofrequencycurrent to deliver said energy into said foreign material to create saidchannel includes delivering said energy into said stent graft.
 15. Amethod as defined in claim 1, further comprising the steps of:monitoring a current output of said electrode; detecting one or moreover-currents if the current output exceeds a predetermined magnitudethreshold; determining an extent of the over-currents detected beforethe expiry of a predetermined time period; and controlling the deliveryof energy based on the extent of the over-currents detected.